An automatic train protection system in general railroad equipment (such as railroad switches, level crossing, railroad lighting) enables a safe operation for the entire vehicle fleet by supervising and controlling the position and the speed of all vehicles (trains) circulating on the railway network in real time.
As being safety relevant, an automatic train protection and railroad equipment system may require a secure power supply. For example, a power interruption at the input of such a system may cause the vehicles to stop operation. Therefore, an automatic train protection and railroad equipment system comprises usually a power supply system that is adapted to provide auxiliary power to the critical loads of the system for a predetermined amount of time. Such power supply systems are also called uninterruptable protection systems.
For example, such a power supply system may interface an available 50 Hz main network to the critical loads and may charge a battery pack while the 50 Hz main network is available. In the case of a power failure, the power supply system will still supply the critical loads via the associated battery pack.
Sometimes the auxiliary power is provided via a diesel electric generator, which may be expensive and poor with respect to an available power density.